In recent time, with the rising interest in stereoscopic imaging services, apparatuses for providing such stereoscopic images are under development. Methods of displaying such stereoscopic images include a stereoscopic scheme, a volumetric scheme, a holographic scheme and the like.
A basic principle of the stereoscopic scheme is to generate a stereoscopic image by separately providing images, which are arranged orthogonal to each other, to user's right and left eyes, and combining the images provided to the respective right and left eyes in a brain. Here, that the images are orthogonally arranged denotes that the images do not interfere with each other.
FIG. 1
FIG. 1 is an exemplary view of a stereoscopic image display device.
A method of implementing a stereoscopic image display device can be classified into a glasses type and a non-glasses type.
The glasses-type includes a polarization type, a time-sequential type, and a spectral type.
First, the polarization type is to separate each image using a polarizing filter. That is, polarizing filters which are orthogonal to each other are applied to an image using a left eye and an image using a right eye, such that different images which are filtered by the polarizing filters can be input to visual fields of the left eye and the right eye.
Next, the time-sequential type is a method of separating each image by displaying a left-eye image and a right-eye image in an alternating manner and synchronizing the alternately displayed images with active glasses worn by a user. That is, when the images are displayed in the alternating manner, a shutter of the active glasses which is synchronized with the corresponding image opens only a visual field to which the corresponding image should be input and blocks the other visual field, thereby inputting the left-eye and right-eye images in the separating manner.
Finally, the spectral type is a method of projecting left-eye and right-eye images through spectrum filters, which have spectrum bands in which RGB spectra do not overlap each other. With regard to the left-eye and right-eye images projected in such a manner, a user wears passive glasses having spectral filters through which only spectral bands set for the left-eye and right-eye images are transmitted, thus to receive the left-eye and right-eye images input in a separating manner.
Meanwhile, the non-glasses type includes a multi-view non-glasses type. The multi-view non-glasses type includes a parallax barrier type and a lenticular lens type.
The parallax barrier type is implemented by coating a barrier (layer) on a display. The barrier (layer) includes perpendicular lines with interposing slits therebetween. The slits generate parallax between a left eye and a right eye.
The lenticular lens type is a method of inputting different images to a left eye and a right eye by arranging refined small lenses on a display and refracting an image using the small lenses.
With the spread of 3D contents and contents having a stereoscopic effect, such 3D or stereoscopic image display devices are widely used. Meanwhile, for utilizing the 3D contents, a multi-view display is used for displaying a stereoscopic image.
FIG. 2
FIG. 2 is a reference view illustrating a multi-view display employed in an image display device.
FIG. 2(a) illustrates a general display. As illustrated in of FIG. 2(a), the general display can show the same screen even if viewing angles (views, view angles or fields of view) of users A, B and C change.
FIG. 2(b) illustrates a multi-view display which is capable of displaying different screens in three displaying directions. As illustrated in FIG. 2(b), the users A, B and C can view different screens from one another according to the changes in viewing angles. This results from a filter which is attached on the multi-view display to restrict (limit) a viewing angle for each pixel.
The multi-view display has an advantage in view of displaying a different screen according to a user's viewing angle.
However, there is a limit that a user can feel a stereoscopic effect, (three-dimensional effect or the sense of dimension). Also, there is a disadvantage in that users who are located within a partial viewing angle area cannot deeply feel the stereoscopic effect. Also, the users cannot feel the stereoscopic effect on a partial region of the display.